1. Field of the Invention
The present invention relates to a method for manufacturing a resin member, where a resilient surface sheet element having sufficient ability to restore itself after being compressed is adhesively attached to a part of a surface of the resin member.
2. Background Information
A resin member prepared by melding a thermoplastic resin is preferably used for casings of electric appliances and interior parts of vehicles, such as instrument panels, door trims, and glove compartments. Such a resin member is formed to a desirable shape by an appropriate molding method, for example, injection molding.
A recent trend has been to give a feeling of softness to a part of the surface of an instrument panel to enhance the value thereof. In a typical instrument panel IP shown in FIG. 1, the feeling of softness is imparted to an upper area A defined by the one-dot chain line, for example, by attaching a skin sheet including a foam layer to the area A. The bonding is typically implemented in accordance with the following steps to prevent the skin sheet from being stripped off the uneven surface of the instrument panel IP.
FIG. 2 is a cross sectional view showing the instrument panel IP taken along line 2--2 of FIG. 1. As shown in FIG. 2, the instrument panel IP consists of a soft member IP1 including the area A and a main member IP2, which are separately manufactured and then securely joined with and bonded to each other. The soft member IP1 is manufactured in the following manner. First, a skin sheet laminate 50 is prepared by laying a foam layer of polypropylene and a skin layer of polyvinyl chloride on one another. The skin sheet laminate 50 is then formed to a predetermined shape with the foam layer thereof positioned on the rear side. A thermoplastic resin such as polypropylene or acrylonitrile-butadiene-styrene copolymer (ABS) is press-formed to a rear face of the skin sheet laminate 50 to form a base element 52 integral with the skin sheet laminate 50. The main member IP2 is manufactured separately by injection molding a thermoplastic resin such as polypropylene or ABS.
The conventional method requires several extra steps for separate manufacture of the soft member IP1 and the main member IP2 as well as subsequent conveyance and assembly of the members IP1 and IP2. The manufacture of the instrument panel IP according to the conventional method undesirably consumes both time and labor. Moreover, lamination of the base element 52 of the soft member IP1 and the main member IP2 makes the final instrument panel IP undesirably heavy.
Some of the extra steps including conveyance may be eliminated by injecting a resin material of the main member IP2 to be integrated with the previously formed skin sheet laminate 50. Injection of the resin material, however, causes a high injection pressure to be locally applied onto the skin sheet laminate 50. This results in excessive compression of the foam layer of the skin sheet laminate 50 or produces crimps on the skin sheet laminate 50, thus lowering the quality of the final instrument panel IP. Crimping may be avoided by press forming the skin sheet laminate 50 together with a thermoplastic resin of the main member IP2. In this case, however, the thermoplastic resin gradually flows along the rear face of the skin sheet laminate 50 to form the main member IP2. This makes the flow of the thermoplastic resin distinctly observable on the exposed resin surface of the main member IP2 to significantly damage the ornamental effects of the surface.